.juzhong(@c:red,@w:200px,@h:200px){
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: auto;
    width: @w;
    height: @h;
    background: @c;
}
*{
    margin: 0;
    padding: 0;
}
#wrap{
    position: relative;
    width: 400px;
    height: 400px;
    margin: 0 auto;
    background: pink;
    .inner{
        .juzhong(deeppink,200px,200px)
    }
    .inner2{
        .juzhong(red,@h:100px)
    }
}